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Pound by Pound, Dollar for Dollar,
The Complicated Equation for Going Green

Doing the Math on Carbon Neutrality

By

Jessica Marmor

Updated April 20, 2007 11:59 p.m. ET

Going green is the new black in 2007. Advice abounds on how to cut your carbon dioxide output and do your part in the battle against global warming. But how much does a person have to spend to go green--and what kind of environmental impact would that spending actually have?

The U.S. is the largest emitter of greenhouse gases in the world, accounting for 25% of the world's total. The average American is responsible for about 20 metric tons a year of CO2 equivalent (CO2e), a standard measure of greenhouse gases. That's about...